Pewter City Gym is the official gym of Pewter City. Brock is the leader of the Pewter Gym located north of Viridan Forest. Many Trainers come here to earn their first gym badge. This Gym specializes in Rock-type Pokémon. Though the designs change throughout the generations, the path is always the same. Beat Brock to earn the Boulder Badge.

Trivia

The Pewter Gym, at least by anime standards, has had the most known Gym Leaders run it with a total of four different Leaders: Brock, Flint, Lola, and Forrest. If Misty's sisters were counted as one Trainer each, Cerulean Gym would tie with it. The gym's type also briefly changes to Water in the anime, when Lola runs the gym.

For unexplained reasons, Pewter Gym seemed to have passed the PIA exam despite having a bad paint job and the Rock Pokémon nearly drowning in the pool, whereas in Cerulean Blues, it is implied that any gym that fails the cleanliness, safety and coolness factors of the exam is shut down.